Deceptive Visualizations

I’m sure there are plenty of examples, but I’ve seen deceptive data visualizations far too often in mass media. I don’t often watch the news, but at times I’ve been at the gym, saw a graph on a television and been a little surprised. The issue is similar to what’s discussed in this SAS article on deceptive graphs.

In this case, the problem is likely what the author describes. An axis was moved, which what I often see in the news. Rather than starting at 0, often the image might start at 20 or 30 on a scale of 1 to 100. As a result, the differences between two bars, lines, or whatever is on the graph is distorted.

This might be unintentional, as more and more graphing tools try to “size to fit” in a space, and can alter graphs, but in many cases, I think the author of the report is deliberately emphasizing something to evoke a reaction in an audience.

I suspect this also happens inside companies. Someone might change scales or axis starting points to emphasize or de-emphasize some part of the data. I could see sysadmins wanting to de-emphasize downtime, but they might want to emphasize a cost savings to get management to make the decision they would prefer.

The article linked above makes a good point. If you do this, your credibility is undermined if someone notices. Maybe the media doesn’t care, but I know that trying to deceive the person that signs your checks, or has some impact on your future employment, is a bad idea. These days, it is hard to find good help, but that doesn’t seem to stop a lot of companies from getting rid of bad help a times.

Present data the way you’d want to see if your positions were reversed. Or if you wanted a decision to be the opposite of that you are hoping for in this instance. You might get a short term win, but in the long term, I would argue your credibility and reputation are worth more than a short term win.

Steve Jones

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